Author Topic: Black Piston  (Read 615 times)

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Offline mdavlee .

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Re: Black Piston
« Reply #10 on: September 20, 2017, 01:22:31 pm »
660 I set to 13k with a tach milling. It woukd be 4 stroking hard at that rpm
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Offline dpjones

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Re: Black Piston
« Reply #11 on: September 21, 2017, 01:05:16 pm »
 I don't think I'm anywhere near that much, I would guess 8 to 10,000 maybe less. I'll hold up on the milling until I get a tach, it's just something I like to do anyway. I do think cut4fun was right about the oil though and me running too rich really added to the problem and me not knowing what I was doing. I aprieciat the help.
Thanks
DJ
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Offline Cut4fun

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Re: Black Piston
« Reply #12 on: September 21, 2017, 01:32:10 pm »
660 I set to 13k with a tach milling. It woukd be 4 stroking hard at that rpm

stock or ported 660?   I was thinking stock max 13.5K.  I know my woods ported one bucking was in 15 range and would 4 stroke like that at lowers.


I don't think I'm anywhere near that much, I would guess 8 to 10,000 maybe less. I'll hold up on the milling until I get a tach, it's just something I like to do anyway. I do think cut4fun was right about the oil though and me running too rich really added to the problem and me not knowing what I was doing. I aprieciat the help.
Thanks
DJ

I dont mill but that sounds fat fat fat to fat

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Offline dpjones

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Re: Black Piston
« Reply #13 on: September 21, 2017, 03:59:43 pm »
I'm only guessing about the rpm's. On all three saws, 038, 029 and 660, if I pushed a little too hard they would start 4-stroking or kinda flooding, I'd let up a little and let them clear out and go again. Just a good light steady push. Now at least I thought that was what was happening.

I took all the guts, cages, out of the mufflers, opened the outlet up on the 29 an 38. Had to heat the crimp with a torch on the 29 to get it apart, then heated it to crimp back.I put a new Walbro WJ-76-1 and a 98cc kit on the 660. The 98cc kit was probably a mistake and may change it back when I check for carbon. I also got a new Cross cylinder kit on the shelf I could put on, one of them MMWS cylinders. Even if it's better it wont cure what I'm doing wrong. I think a tach may at the least tell me where I'm at with the rpm's, my ear don't seem to be doing it.
Thanks

Offline Cut4fun .

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Re: Black Piston
« Reply #14 on: September 21, 2017, 04:07:55 pm »
Before you buy the wrong tach. Info from 2011 to 2017 so far. https://chainsawrepair.createaforum.com/stickys-of-how-to-basics/chainsaw-tachometer-choices/
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Offline mdavlee .

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Re: Black Piston
« Reply #15 on: September 21, 2017, 09:35:32 pm »
Yeah if they're that rich it will really make a mess with the heat from milling. I tuned ported 660s to 13k milling.
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Offline deezlfan

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Re: Black Piston
« Reply #16 on: September 22, 2017, 09:41:25 am »
Using my hillbilly, back forty edjuamacation, I'm gonna say you are overheating the oil beyond it's capabilities. The black is obviously carbon. The only sensible place carbon can come from is the oil. I find it hard to believe that the carb settings could be so rich that you could build up that much residue. [If it was, that saw would smoke like a diesel rollin' coal!!] Opening up the muffler should reduce the cylinder temps.  Also are you keeping the powerhead as far away from the work as is possible? I've seen many guys mod the muffler on the front face and then let the saw pull up tight in the cut blocking exhaust flow. 
We just drag them down..... Until they're just like us !!!  BNL

Offline Cut4fun .

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Re: Black Piston
« Reply #17 on: September 22, 2017, 10:53:47 am »
Just my WAG on the reason. Heat = using the Super Tech oil with 20% Benol  castor oil caramelize on piston.   
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Offline Cut4fun .

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Re: Black Piston
« Reply #18 on: September 22, 2017, 10:56:45 am »
This was a husky 562 stumpy did running 32:1 with super tech  no no ;)

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Offline dpjones

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Re: Black Piston
« Reply #19 on: September 22, 2017, 11:55:48 am »
That looks the same as mine, wouldn't it do the same in a dirt bike? When my son had a Suzuki 125 RM I think, very powerful, that's what we were told was best to run and we did. I rebuilt it and don't remember that or stuck rings so I thought it be good for saws or any 2-stroke. Guess not

 

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